I have heavily used these mitts winter biking and backcountry skiing over the last two winters. The Revel mitts kept my hands toasty down to -20 degC depending on what gloves/mitts I wore under them. They have been quite durable so far, although little holes on the thumbs and the tip of the fingers started showing up this winter. As such, the mitts are not entirely waterproof anymore. They still do OK in light rain or moist snow, but if I know Iï¾'ll be doing a lot of digging or I am out on overnight trips, I bring Gore-Tex gloves along. Although not fully waterproof anymore, the mitts are still amazing at blocking wind and are very breathable. Plus, I really like the reflective details for winter biking. They will still be my go-to shell mitts next winter!